discredit (v.)

1550s, "disbelieve, give no credit to," from dis- "opposite of" + credit (v.). Meaning "show to be unworthy of belief" is from 1560s; that of "injure the reputation of, make less esteemed or honored" is from 1570s. As a noun, "want of credit or good repute," 1560s, from the verb. Related: Discredited; discrediting.

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Definitions of discredit from WordNet
discredit (v.)
cause to be distrusted or disbelieved;
The paper discredited the politician with its nasty commentary
discredit (v.)
damage the reputation of;
This newspaper story discredits the politicians
Synonyms: disgrace
discredit (v.)
reject as false; refuse to accept;
Synonyms: disbelieve
discredit (n.)
the state of being held in low esteem;
your actions will bring discredit to your name
Synonyms: disrepute